This invention relates to a method and a device for the thermal treatment of substrates, in particular flat substrates in the production of semiconductors.
When producing components in the field of the semiconductor industry, it is known to treat substrates thermally in a heating device, as is known, for example, from DE 100 59 885 C1, which derives from the applicant of the present application, or from DE 199 07 497 C, which also derives from the applicant. A common process step is, for example, the hardening of a lacquer after lacquering, and the so-called “Post-Exposure Bake” (PEB) for fixing “Chemically Amplified Resists” (CAR) after an exposure. For the quality of the structures and the result of the thermal treatment an even, homogeneous supply of heat info the substrate, in particular into a layer thereon, is of decisive significance. This is not easily possible in particular with angular substrates with a great material thickness, such as for example photomasks, because during the heating of the substrate there is more mass to he heated in the center relative to the edges, and the center therefore warms up more slowly relative to the edges. On the other hand, after reaching a final temperature, the edges radiate more heat relative to the center due to the greater surface such that they cool down more quickly after reaching the final temperature. This same problem also occurs of course with round semiconductor substrates.
In order to overcome this problem, in the past a heating device with several actively regulated zones was used, as is known from the aforementioned DE 189 07 497 C, as was a self-optimizing control method according to DE 100 59 666 C1. By means of these healing devices it was possible to heat the center of a substrate during the heat-op phase more strongly relative to the edges, and after reaching the final temperature, to heat the edges more strongly relative to the center.
Although the known device and the known control method bring good results, there is still the need to further increase the temperature homogeneity during thermal treatments, in particular for photomasks of the next generation (65 nm node).
Starting from the known prior art, it is therefore an object of the present invention to provide a method and a device for the thermal treatment of substrates with which improved homogeneity of a thermal treatment can be achieved.